Sec Form 4 Filing - HEARTLAND INDUSTRIAL ASSOCIATES LLC @ TRIMAS CORP - 2013-02-27

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person HEARTLAND INDUSTRIAL ASSOCIATES LLC 2. Issuer Name and Ticker or Trading Symbol TRIMAS CORP [ TRS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director X __ 10% Owner _____ Officer (give title below) X __ Other (specify below) See Footnote 1 (Last) (First) (Middle) 177 BROAD STREET, 10TH FLOOR 3. Date of Earliest Transaction (MM/DD/YY) 02/27/2013 (Street) STAMFORD, CT06901 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Stock 02/27/2013 S 1,500,000 D $ 28.71 2,404,972 I See Footnotes ( 1 ) ( 2 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other HEARTLAND INDUSTRIAL ASSOCIATES LLC 177 BROAD STREET 10TH FLOOR STAMFORD, CT06901 X See Footnote 1 Signatures Daniel P. Tredwell 03/01/2013 Signature of Reporting Person Date

Explanation of Responses:

( 1 )These securities are owned directly by Metaldyne Investment Fund I, L.L.C. ("MIF I"). MIF I will sell 1,500,000 shares. Following the sale of these securities, MIF I will own 743,827 shares. Heartland Industrial Partners, L.P. ("Heartland Partners"), as the managing member of MIF I, and Heartland Industrial Associates L.L.C. ("Heartland"), as the General Partner of Heartland Partners, may each be deemed to be an indirect beneficial owner of the securities held by MIF I and each disclaims beneficial ownership (as defined in Rule 16a-1(a)(2)) of these securities except to the extent of its pecuniary interest therein. ( 2 )Heartland, Heartland Partners and MIF I may be deemed to be members of a group for purposes of Section 13(d) of the Securities Exchange Act of 1934.

Remarks: Signature by Daniel P. Tredwell, as Managing Member of Heartland, which is General Partner of Heartland Partners, which is managing member of MIF I.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).

** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).

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